feat: add hunt page, combat placeholder, and Jagd navigation

Wires up Slice 0.2 end-to-end: HuntPageComponent renders the
hunting-unavailable/ready/loading/encounters-found states off
HuntingStore and WorldStore, Angreifen hands the HuntEncounter id to a
new inert CombatPlaceholderPageComponent via /combat/new, the Jagd nav
entry is enabled with router-driven active state (matching Karte's),
and the context panel now lists possible encounters for hunting-enabled
locations.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/src/app/layout/side-navigation/side-navigation.component.ts

@@ -1,9 +1,9 @@
 import { Component } from '@angular/core';
-import { RouterLink } from '@angular/router';
+import { RouterLink, RouterLinkActive } from '@angular/router';
 
 @Component({
   selector: 'app-side-navigation',
-  imports: [RouterLink],
+  imports: [RouterLink, RouterLinkActive],
   templateUrl: './side-navigation.component.html',
   styleUrl: './side-navigation.component.scss',
 })